Organic Light-Emitting Diode (OLED) display devices have been considered as the display devices with the greatest potential due to their advantages such as self-luminescence, low driving voltage, high light-emitting efficiency, rapid response speed, high definition and contrast, a wide viewing angle of about 180°, a wide operating temperature range, and being capable of achieving flexible display as well as large-area full-color display.
Along with the development of the technology, Active Matrix Organic Light-Emitting Diode (AMOLED) display device with a large size and a high resolution have been widely used. For the AMOLED display device, an identical power voltage (VDD) is applied to all subpixels. However, a voltage drop (IR drop) may inevitably occur due to a wire resistance in the case that a VDD signal is transmitted on a wire, so the actual power voltages applied to the subpixels may be different from each other. At this time, the subpixels may emit light at different brightness values in the case of an identical data signal, resulting in uneven display brightness.
In addition, in the case of image change, the voltage drop may change along with a driving current.
For a conventional display driver circuit, the voltage drop compensation is performed on a subpixel basis. Taking a mainstream ultra high definition display panel with a resolution of 3840*2160 as an example, compensation amounts for about 10,000,000 (8,294,400 exactly) subpixels may be calculated within one frame (a dozen of milliseconds). To be specific, for each subpixel, at least of the following items need to be calculated: a current ideal current for the subpixel, a VDD voltage drop corresponding to the current, a brightness reduction amount due to the VDD voltage drop, a data signal compensation amount for compensating for the brightness reduction amount, and a data signal after the compensation.
It is found that, the calculation burden is extremely large in the case that the voltage drop compensation is performed for each subpixel, and it is impossible for the conventional display driver circuit to achieve the large-scale application.